Early in the Hellenistic period the Academy went sceptic, until the beginning of the first century BC. The philosopher who effected this change of outlook in the Academy was Arcesilaus. The most notable of Arcesilaus' sceptical successors was Carneades. In the course of his engagement with both Stoicism and Epicureanism, Carneades worked out for the first time in Greek philosophy an alternative non-foundationalist epistemology, sometimes misleadingly dubbed probabilism. The dialectical interpretation can appeal to Arcesilaus' well-attested revival of the Socratic method. The main thesis to which Arcesilaus is said to have subscribed is the claim that nothing is known for certain, or more precisely that there is no such thing as what the Stoics called cognition. There are two objections to Arcesilaus' position, one theoretical, and another practical. Carneades and the Academy in general agreed with Arcesilaus in arguing against the cognitive impression.

CouissinP. (1929) ‘Le stoïcisme de la Nouvelle Académie’, Revue d'Histoire de la Philosophie Générale de la Civilisation3. Cited in the English version (1983) ‘The Stoicism of the New Academy’, in Burnyeat (1983).